Common carriers, such as passenger airlines, bus lines, and train lines, frequently convey substantial numbers of passengers simultaneously. In many instances, there is a desire to increase the number of seats within a given space to optimize the number of passengers being transported at any given time, such as in economy class seating in aircraft as an example.
By increasing the number of passenger seats in the space, the amount of space available between seats arranged in a column (also known as pitch) is diminished. For example, a desirable pitch may be a small as 27 inches or less. Typically, the amount by which pitch can be reduced is usually constrained by the dimension of the passenger seat that is in the area of a passenger's knees located behind a seat back of the passenger seat.
In conventional economy seating, the passenger seats typically provide some amount of recline adjustment for the seat back. The reclining function requires additional pitch to allow the seat back to recline without impacting the passenger's knees. In some economy seating arrangements, the pitch has been somewhat reduced by eliminating the recline function altogether or at least reconfiguring the seat back so that only the portion of the seat back above the knee area reclined. However, even with these changes, additional pitch reduction is desired for certain applications.
Another factor that influences the amount by which pitch may be reduced is related to safety regulations designed to minimize injuries during a crash. For example, due to the small pitch between two rows of seats, passengers seated in the second row of seats will typically impact the seat backs of the seats in the first row during a crash. For aircraft passenger seats, current safety regulations require performance of various crash tests with two rows of seats spaced apart at the targeted pitch, while dummies are positioned in the second row of seats. In these crash tests, the so-called Head Injury Criterion (“HIC”) has to remain at or below a value of 1000.
Conventionally, energy dissipation solutions focused on allowing the passenger seatback to pivot forward in a controlled manner via features located in the lower back area of the passenger seatback that give way under a certain load. Generally, these features include metallic brackets with a designed shear area or shear bolts that are attached to the back diaphragm of the seat. For example, these seats rely on mechanical fuse parts or other energy absorbing devices to absorb the crash impact force to achieve an acceptable HIC value.
Components of these seats typically include vertical legs attached to the seat track of the aircraft, one or more transverse beams, spreaders between each individual seat to which the seat belt is attached, seat pans, seat backs (fixed or reclinable), and other features, such as armrests, tray tables, etc.
Thus, it may be desirable to provide a seat with lighter weight and thinner components to provide additional reductions in pitch and weight, while also providing an acceptable HIC value.